Nib for writing instrument

ABSTRACT

A nib for writing instrument is provided which comprises a core member having a plurality of radial legs longitudinally extending along the length of the nib, subcore elements each being substantially triangular in section and having a groove or grooves on each side thereof, and a tubular shroud having a thin wall to enclose outer peripheral surfaces of the legs of the core member and the subcore members. A plurality of ink feeding channels for capillary action are formed at least between the subcore elements and the legs, and between the subcore elements and the tubular shroud.

Unite ttea Patet [191 Kolmo et al.

[ Aug. 20, 3974 NlB FOR WRllTlNG llNSTRlJMENT Inventors: Tadaslii Kolmo, Koshigaya; Tsuguo Watanabe, Tokyo, both of Japan Assignee: Pentel Kahusliiki Kaisha, Tokyo,

Japan Filed: Aug. 8, 1972 Appl. No.: 278,870

Foreign Application Priority Data Aug. 10, 1971 Japan 46-71421 U.S. Cl 4011/292, 401/199, 401/265 Int. Cl 343k 8/00 Field of Search 401/198, 199, 284, 292,

References Cited UNITED STATES PATENTS l/1969 Jenkins 401/292 Funahashi 401/284 X Kiriu 401/199 Primary Examiner-Lawrence Charles Attorney, Agent, or Firm-Eliot S. Gerber 57 ABSTRACT 1 Claim, 9 Drawing Figures PATENTEDAUEZOIHH sum 2 or 2 F|ca.9

NIB FQR WRITING INSTRNT This invention relates to a nib for writing instruments and more particularly to a writing nib of the type having capillary ink feeding channels through which ink is continuously fed to a writing point from an ink reservoir.

Many proposals have been made to provide writing instruments, one of which comprises a number of mono-filaments each having a circular shape in cross section, said mono-filaments being enclosed by a thinwalled tubular housing except tapered writing tip portion as described in U.S. Pat. No. 3,203,025.

Another writing instrument has been proposed which comprises a star-shaped core member, in cross section, and a plurality of subcore elements each of which has a control opening for effecting the capillary action therethrough. The core member and the subcore elements are enclosed by a thin-walled tubular housing except tapered writing tip portion as described in U.S. Pat. No. 3,604,817.

However, according to the known writing instruments, particularly to the former described U.S. Pat. No. 3,203,025 the mono-filaments at the tapered writing tip portion may be separated from each other while using and may catch the writing surface with the result that smooth writing will be disturbed. Moreover, when the mono-filaments caught on the writing surface are freed and recovered to the original state, ink splashes abnormally to spoil the writing surface.

In the latter described known instrument, i.e., U.S. Pat. No. 3,604,817 since it is only the tip portion of the star-shaped core member that contacts a surface to be written, the subcore elements do not catch the surface, thereby eliminating any splashing of ink. However, according to the structure of the writing instrument shown in the latter patent, ink is flowed through capillary channels disposed at the center of the subcore elements, whose peripheries are entirely closed by the core member and the tubular housing. Therefore, ink is easy to stop flowing especially when the ink includes some pigments. Furthermore, according to the structure above, ink is forced to flow abnormally much to cause a dropping of ink especially when air expands in ink reservoir.

Furthermore, since the star-shaped core member 'is provided with several legs each of which becomes thinner along the outwardly extending end thereof, a writing point to be contact with a paper surface has a rather large area. Therefore, when the writing nib is so sharpened for writing fine lines, ink will not reach the writing point continuously.

Accordingly, an object of the present invention is to provide an improved nib for writing instruments wherein ink flows continuously to its writing point without any dropping, clogging and splashing of ink.

Another object of the present invention is to provide an improved nib for writing instruments which allows ink to flow traversely from the center to periphery of the writing nib and reversely when a writing pressure is applied to and eliminated from the writing nib.

A nib for writing instruments according to the present invention fundamentally comprises a core member, a plurality of subcore elements, and a tubular shroud enclosing the core member and the subcore elements. All of them are made of synthetic resin such as polyacetal, polyester, or polyamide. The core member has a plurality, of radial legs longitudinally extending with a substantially constant thickness and with equal angles from a center body portion to an end portion thereof. Each of the subcore elements is solid and substantially triangular shaped in section, and has a groove or grooves on each triangular side along the longitudinal direction thereof. The subcore elements having grooves thereon are positioned between the legs to form capillary ink feeding channels therebetween.

The aforementioned and other objects and features of the present invention will be apparent from the following detailed description of specific embodiments thereof, when read in conjunction with the accompanying drawings, in which:

FIG. 11 is a partially cut away perspective view of a nib for writing instruments according to the present invention.

FIGS. 2 and 3 are diagrammatic plane views of different types of subcore elements to be employed in the writing nib according to the present invention.

FIGS. 4 through 8 are cross sectioned views of writing nibs according to different embodiments of the present invention.

FIG. 9 is a partially cut away perspective view of a nib for writing instrument according to another embodiment of the present invention, showing a plurality of minor grooves formed in parallel on the longitudinal sides of the legs.

In the drawings a core member 1 comprises a plurality of legs 2 radially extending with substantially equal angles which also extend longitudinally. Each of the legs has a substantially constant thickness from a center body portion to an end portion thereof, and is made of synthetic resin such as polyacetal, polyester, or polyamide. The legs may be provided as many as three as shown in FIGS. 1, 4, 5 and 6, or six as shown in FIGS. 7 and 8. Thickness and length of the legs 2 are about 0.05 to 0.3 mm and 0.1 to 1.0 mm, respectively.

Though the legs 2 of the embodiments shown in Figures have smooth surfaces on their longitudinal sides, they may be provided with a number of minor grooves to facilitate ink capillary action.

Though the legs 2 of the embodiments shown in FIGS. 1 through 8 have smooth surfaces on their longitudinal sides, they may be provided with a number of parallel minor grooves 6, as shown in FIG. 9.

Each subcore element 4 made of synthetic resin has a substantially triangular prism shape, on each triangular side of which is provided with groove or grooves along the longitudinal direction thereof. The subcore elements 4 are each positioned between the adjoining legs 2 as shown in FIGS. 7 and 8, and may be preferably positioned in pairs between the adjoining legs as shown in FIGS. 4, 5, and 6.

Preferable configurations of the subcore elements 4 are shown in FIGS. 2 and 3. The subcore element in FIG. 2 has one curved groove on its each triangular side, the grooves having ends terminating at apexes of said triangular shape, respectively. The dimensions of each subcore are such that the side A is in the range of from 0.51 to 0.63 mm, the width B of the groove is from 0.25 to 0.45, and the depth of the groove D is from 0.04 to 0.12 mm. The subcore element shown in FIG. 3 has a plurality of wave shaped grooves whose depth is less than 0.04 mm. The most preferable number of the grooves is three as shown in FIG. 3.

Preferable examples of combination of the core member I and the subcore elements are shown in FIGS. 4, 5, and 6, in which three legs and three pairs of subcore elements are provided so that each pair of the subcore elements may be snugly positioned between the adjoining legs. In FIG. 4, the subcore elements of the type shown in FIG. 2 are employed. In FIG. 5, the subcore elements of the type shown in FIG. 3 are employed. In FIG. 6, each pair of the subcore elements consisting of a subcore element of the type shown in FIG. 2 and a subcore element of the type shown in FIG. 3 are employed. The arrangement of the subcore elements of a pair shown in FIG. 6 may be changed with each other.

Other embodiments according to the present invention are shown in FIGS. 7 and 8 each of which has six legs and six subcore elements respectively. In FIG. 7 the subcore elements of the type shown in FIG. 2 are employed, while the elements shown in FIG. 3 are employed in the embodiment shown in FIG. 8.

A tubular shroud encloses the outer peripheral surfaces of the legs 2 of the core member I and the subcore elements to form an integrally combined body. Ink feeding channels 3 are formed or left between the legs 2 and the subcore elements 1-, between the tubular shroud 5 and the subcore elements 4, and also between adjacent pair of subcore elements 4 when preferable structure of paired subcore elements is employed. The tubular shroud is a thin-walled tubular housing which is as thick as 0.2 to 0.5 mm and is made of synthetic resins such as polyvinyl chloride, polyethelane, or polyasetal.

Such materials enclosed by the tubular shroud as described above are cut at predetermined length to form a tapered writing tip portion terminating at a writing point.

According to the writing nib of the present invention, the center body portion of the core member 1 has a relatively small area at the writing point comparing with the known writing instrument which has the starshaped core member. The cross section of the writing point to be contact with writing surfaces includes parts of the subcore elements adjacent to the center body portion of the core member. Therefore, the capillary ink feeding channels are still formed at the writing point between the center body portion of the core member and the parts of the subcore elements. Moreover, as the subcore elements 4 each provided with a plurality of grooves are confined by the core member I and the tubular shroud, when a writing pressure enough to bend the flexible nib is applied to the writing point of the nib, the capillary ink feeding channels between the relatively rigid core member, the relatively flexible subcore elements and the shroud are somewhat varied to allow the ink to move toward and away from the central body portion of the core member. Thus, the ink flows traversely from the ink feeding channels to the other channels and is homogeneously supplied to the writing point. Furthermore, as the capillary ink feeding channels are varied by slight movement of the subcore elements due to flexion thereof, the subcore elements function for cleaning of the capillary channels by themselves so as not to blockade the latter.

Furthermore, each side of the legs 2 having a constant thickness holds firmly the subcore elements therebetween. Therefore, ink never splashes even when the tapered tip portion of the subcore elements contacts paper or the like, and smooth writing is insured.

Though the present invention has been described with reference to the preferred embodiments thereof, many modifications and alterations may be made within the spirit of the present invention.

What is claimed is:

l. A nib structure for a writing instrument comprising a core member having three legs radially extending from the center of said core member, said egs having substantially equal thickness and extending from said center with substantially equal angles, three pairs of subcore elements, each of said subcore elements being solid and substantially triangular shaped in section and having a groove or grooves formed on each triangular side along the longitudinal direction thereof so that each side of the triangular sides of the same subcore element has the same surface shape, and a tubular shroud enclosing outer peripheral surfaces of said legs and said subcore elements, except, at least at the sharpened writing tip portion thereof, said tubular shroud holding said subcore elements to said core member to provide capillary ink feeding channels between said tubular shroud and said grooved outer peripheral surface of said subcore elements, wherein said subcore elements of each pair are snugly disposed side by side between adjoining legs of said core member with capillary ink feeding channels between said legs and the grooved surface of said subcore elements and between the grooved surfaces of said pair of subcore elements, said each pair of subcore elements are constructed with two subcore elements with different shaped surfaces from each other, and each of said legs has a thickness of 0.05

to 0.3 mm and a length of 0.1 to 1.0 mm. 

1. A nib structure for a writing instrument comprising a core member having three legs radially extending from the center of said core member, said egs having substantially equal thickness and extending from said center with substantially equal angles, three pairs of subcore elements, each of said subcore elements being solid and substantially triangular shaped in section and having a groove or grooves formed on each triAngular side along the longitudinal direction thereof so that each side of the triangular sides of the same subcore element has the same surface shape, and a tubular shroud enclosing outer peripheral surfaces of said legs and said subcore elements, except, at least at the sharpened writing tip portion thereof, said tubular shroud holding said subcore elements to said core member to provide capillary ink feeding channels between said tubular shroud and said grooved outer peripheral surface of said subcore elements, wherein said subcore elements of each pair are snugly disposed side by side between adjoining legs of said core member with capillary ink feeding channels between said legs and the grooved surface of said subcore elements and between the grooved surfaces of said pair of subcore elements, said each pair of subcore elements are constructed with two subcore elements with different shaped surfaces from each other, and each of said legs has a thickness of 0.05 to 0.3 mm and a length of 0.1 to 1.0 mm. 